Before the ice ages started around 40 million years ago, the world had no ice at the poles.
The cool down was driven in part by formation of the Himalayas, so weathering pulled a lot of CO2 out of the atmosphere. (Note, CO2 levels have been much higher in Earth’s history, and life was fine.) The world went into a deep chill as well because South America separated from Antarctica, allowing the currents to form around that continent, winds follow currents, and that continent changed from Alaska cold to two mile thick ice.
In short, Earth’s still five to ten degrees Celsius below its historic norm, and it is cooler today than it was during the Medieval Warm Period and other warmer periods during this current interglacial.
But we absolutely don’t want it to get colder.
Lettin’ the Hemi idle in the driveway. Which is actually, right now, a parking spot with snow on it.